https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109569
Bug ID: 109569
Summary: warning: ‘void* __builtin_memmove(void*, const void*,
long unsigned int)’ writing 1 or more bytes into a
region of size 0 overflows the destination
[-Wstringop-overflow=]
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: f.heckenb...@fh-soft.de
Target Milestone: ---
Unlike most of the other issues I reported today, this one doesn't seem so
harmless, or is it?
How can I avoid it; should I just disable this warning?
Removing the shared_ptr makes it go away, even though the shared_ptr is
completely unused (in this code -- I need it in my actual code).
% cat test.cpp
#include <vector>
#include <memory>
struct D
{
const char *s = "a";
std::shared_ptr <int> p;
D (std::shared_ptr <int> p_ = { }): p (p_) { }
};
struct T
{
std::vector <char> v;
T ()
{
D d;
v.insert (v.end (), d.s, d.s + 1);
}
};
int main ()
{
T t;
}
% g++ -c -std=c++20 -Wall -Wextra -O2 test.cpp
In file included from /usr/include/c++/12/vector:60,
from test.cpp:1:
In static member function ‘static constexpr _Tp* std::__copy_move<_IsMove,
true, std::random_access_iterator_tag>::__copy_m(const _Tp*, const _Tp*, _Tp*)
[with _Tp = char; bool _IsMove = true]’,
inlined from ‘constexpr _OI std::__copy_move_a2(_II, _II, _OI) [with bool
_IsMove = true; _II = char*; _OI = char*]’ at
/usr/include/c++/12/bits/stl_algobase.h:495:30,
inlined from ‘constexpr _OI std::__copy_move_a1(_II, _II, _OI) [with bool
_IsMove = true; _II = char*; _OI = char*]’ at
/usr/include/c++/12/bits/stl_algobase.h:522:42,
inlined from ‘constexpr _OI std::__copy_move_a(_II, _II, _OI) [with bool
_IsMove = true; _II = char*; _OI = char*]’ at
/usr/include/c++/12/bits/stl_algobase.h:529:31,
inlined from ‘constexpr _OI std::copy(_II, _II, _OI) [with _II =
move_iterator<char*>; _OI = char*]’ at
/usr/include/c++/12/bits/stl_algobase.h:620:7,
inlined from ‘static _ForwardIterator
std::__uninitialized_copy<true>::__uninit_copy(_InputIterator, _InputIterator,
_ForwardIterator) [with _InputIterator = std::move_iterator<char*>;
_ForwardIterator = char*]’ at
/usr/include/c++/12/bits/stl_uninitialized.h:147:27,
inlined from ‘_ForwardIterator std::uninitialized_copy(_InputIterator,
_InputIterator, _ForwardIterator) [with _InputIterator = move_iterator<char*>;
_ForwardIterator = char*]’ at
/usr/include/c++/12/bits/stl_uninitialized.h:185:15,
inlined from ‘constexpr _ForwardIterator
std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator,
allocator<_Tp>&) [with _InputIterator = move_iterator<char*>; _ForwardIterator
= char*; _Tp = char]’ at /usr/include/c++/12/bits/stl_uninitialized.h:372:37,
inlined from ‘constexpr _ForwardIterator
std::__uninitialized_move_if_noexcept_a(_InputIterator, _InputIterator,
_ForwardIterator, _Allocator&) [with _InputIterator = char*; _ForwardIterator =
char*; _Allocator = allocator<char>]’ at
/usr/include/c++/12/bits/stl_uninitialized.h:397:2,
inlined from ‘constexpr void std::vector<_Tp,
_Alloc>::_M_range_insert(iterator, _ForwardIterator, _ForwardIterator,
std::forward_iterator_tag) [with _ForwardIterator = const char*; _Tp = char;
_Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/vector.tcc:801:9,
inlined from ‘constexpr void std::vector<_Tp,
_Alloc>::_M_insert_dispatch(iterator, _InputIterator, _InputIterator,
std::__false_type) [with _InputIterator = const char*; _Tp = char; _Alloc =
std::allocator<char>]’ at /usr/include/c++/12/bits/stl_vector.h:1779:19,
inlined from ‘constexpr std::vector<_Tp, _Alloc>::iterator std::vector<_Tp,
_Alloc>::insert(const_iterator, _InputIterator, _InputIterator) [with
_InputIterator = const char*; <template-parameter-2-2> = void; _Tp = char;
_Alloc = std::allocator<char>]’ at
/usr/include/c++/12/bits/stl_vector.h:1481:22,
inlined from ‘T::T()’ at test.cpp:17:14:
/usr/include/c++/12/bits/stl_algobase.h:431:30: warning: ‘void*
__builtin_memmove(void*, const void*, long unsigned int)’ writing 1 or more
bytes into a region of size 0 overflows the destination [-Wstringop-overflow=]
431 | __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
| ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from
/usr/include/x86_64-linux-gnu/c++/12/bits/c++allocator.h:33,
from /usr/include/c++/12/bits/allocator.h:46,
from /usr/include/c++/12/vector:61:
In member function ‘_Tp* std::__new_allocator<_Tp>::allocate(size_type, const
void*) [with _Tp = char]’,
inlined from ‘constexpr _Tp* std::allocator< <template-parameter-1-1>
>::allocate(std::size_t) [with _Tp = char]’ at
/usr/include/c++/12/bits/allocator.h:188:40,
inlined from ‘static constexpr _Tp*
std::allocator_traits<std::allocator<_Up> >::allocate(allocator_type&,
size_type) [with _Tp = char]’ at
/usr/include/c++/12/bits/alloc_traits.h:464:28,
inlined from ‘constexpr std::_Vector_base<_Tp, _Alloc>::pointer
std::_Vector_base<_Tp, _Alloc>::_M_allocate(std::size_t) [with _Tp = char;
_Alloc = std::allocator<char>]’ at
/usr/include/c++/12/bits/stl_vector.h:378:33,
inlined from ‘constexpr std::_Vector_base<_Tp, _Alloc>::pointer
std::_Vector_base<_Tp, _Alloc>::_M_allocate(std::size_t) [with _Tp = char;
_Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/stl_vector.h:375:7,
inlined from ‘constexpr void std::vector<_Tp,
_Alloc>::_M_range_insert(iterator, _ForwardIterator, _ForwardIterator,
std::forward_iterator_tag) [with _ForwardIterator = const char*; _Tp = char;
_Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/vector.tcc:787:40,
inlined from ‘constexpr void std::vector<_Tp,
_Alloc>::_M_insert_dispatch(iterator, _InputIterator, _InputIterator,
std::__false_type) [with _InputIterator = const char*; _Tp = char; _Alloc =
std::allocator<char>]’ at /usr/include/c++/12/bits/stl_vector.h:1779:19,
inlined from ‘constexpr std::vector<_Tp, _Alloc>::iterator std::vector<_Tp,
_Alloc>::insert(const_iterator, _InputIterator, _InputIterator) [with
_InputIterator = const char*; <template-parameter-2-2> = void; _Tp = char;
_Alloc = std::allocator<char>]’ at
/usr/include/c++/12/bits/stl_vector.h:1481:22,
inlined from ‘T::T()’ at test.cpp:17:14:
/usr/include/c++/12/bits/new_allocator.h:137:55: note: at offset 1 into
destination object of size 1 allocated by ‘operator new’
137 | return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n *
sizeof(_Tp)));
| ^
In static member function ‘static constexpr _Tp* std::__copy_move<_IsMove,
true, std::random_access_iterator_tag>::__copy_m(const _Tp*, const _Tp*, _Tp*)
[with _Tp = char; bool _IsMove = true]’,
inlined from ‘constexpr _OI std::__copy_move_a2(_II, _II, _OI) [with bool
_IsMove = true; _II = char*; _OI = char*]’ at
/usr/include/c++/12/bits/stl_algobase.h:495:30,
inlined from ‘constexpr _OI std::__copy_move_a1(_II, _II, _OI) [with bool
_IsMove = true; _II = char*; _OI = char*]’ at
/usr/include/c++/12/bits/stl_algobase.h:522:42,
inlined from ‘constexpr _OI std::__copy_move_a(_II, _II, _OI) [with bool
_IsMove = true; _II = char*; _OI = char*]’ at
/usr/include/c++/12/bits/stl_algobase.h:529:31,
inlined from ‘constexpr _OI std::copy(_II, _II, _OI) [with _II =
move_iterator<char*>; _OI = char*]’ at
/usr/include/c++/12/bits/stl_algobase.h:620:7,
inlined from ‘static _ForwardIterator
std::__uninitialized_copy<true>::__uninit_copy(_InputIterator, _InputIterator,
_ForwardIterator) [with _InputIterator = std::move_iterator<char*>;
_ForwardIterator = char*]’ at
/usr/include/c++/12/bits/stl_uninitialized.h:147:27,
inlined from ‘_ForwardIterator std::uninitialized_copy(_InputIterator,
_InputIterator, _ForwardIterator) [with _InputIterator = move_iterator<char*>;
_ForwardIterator = char*]’ at
/usr/include/c++/12/bits/stl_uninitialized.h:185:15,
inlined from ‘constexpr _ForwardIterator
std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator,
allocator<_Tp>&) [with _InputIterator = move_iterator<char*>; _ForwardIterator
= char*; _Tp = char]’ at /usr/include/c++/12/bits/stl_uninitialized.h:372:37,
inlined from ‘constexpr _ForwardIterator
std::__uninitialized_move_if_noexcept_a(_InputIterator, _InputIterator,
_ForwardIterator, _Allocator&) [with _InputIterator = char*; _ForwardIterator =
char*; _Allocator = allocator<char>]’ at
/usr/include/c++/12/bits/stl_uninitialized.h:397:2,
inlined from ‘constexpr void std::vector<_Tp,
_Alloc>::_M_range_insert(iterator, _ForwardIterator, _ForwardIterator,
std::forward_iterator_tag) [with _ForwardIterator = const char*; _Tp = char;
_Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/vector.tcc:801:9,
inlined from ‘constexpr void std::vector<_Tp,
_Alloc>::_M_insert_dispatch(iterator, _InputIterator, _InputIterator,
std::__false_type) [with _InputIterator = const char*; _Tp = char; _Alloc =
std::allocator<char>]’ at /usr/include/c++/12/bits/stl_vector.h:1779:19,
inlined from ‘constexpr std::vector<_Tp, _Alloc>::iterator std::vector<_Tp,
_Alloc>::insert(const_iterator, _InputIterator, _InputIterator) [with
_InputIterator = const char*; <template-parameter-2-2> = void; _Tp = char;
_Alloc = std::allocator<char>]’ at
/usr/include/c++/12/bits/stl_vector.h:1481:22,
inlined from ‘T::T()’ at test.cpp:17:14:
/usr/include/c++/12/bits/stl_algobase.h:431:30: warning: ‘void*
__builtin_memmove(void*, const void*, long unsigned int)’ writing 1 or more
bytes into a region of size 0 overflows the destination [-Wstringop-overflow=]
431 | __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
| ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In member function ‘_Tp* std::__new_allocator<_Tp>::allocate(size_type, const
void*) [with _Tp = char]’,
inlined from ‘constexpr _Tp* std::allocator< <template-parameter-1-1>
>::allocate(std::size_t) [with _Tp = char]’ at
/usr/include/c++/12/bits/allocator.h:188:40,
inlined from ‘static constexpr _Tp*
std::allocator_traits<std::allocator<_Up> >::allocate(allocator_type&,
size_type) [with _Tp = char]’ at
/usr/include/c++/12/bits/alloc_traits.h:464:28,
inlined from ‘constexpr std::_Vector_base<_Tp, _Alloc>::pointer
std::_Vector_base<_Tp, _Alloc>::_M_allocate(std::size_t) [with _Tp = char;
_Alloc = std::allocator<char>]’ at
/usr/include/c++/12/bits/stl_vector.h:378:33,
inlined from ‘constexpr std::_Vector_base<_Tp, _Alloc>::pointer
std::_Vector_base<_Tp, _Alloc>::_M_allocate(std::size_t) [with _Tp = char;
_Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/stl_vector.h:375:7,
inlined from ‘constexpr void std::vector<_Tp,
_Alloc>::_M_range_insert(iterator, _ForwardIterator, _ForwardIterator,
std::forward_iterator_tag) [with _ForwardIterator = const char*; _Tp = char;
_Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/vector.tcc:787:40,
inlined from ‘constexpr void std::vector<_Tp,
_Alloc>::_M_insert_dispatch(iterator, _InputIterator, _InputIterator,
std::__false_type) [with _InputIterator = const char*; _Tp = char; _Alloc =
std::allocator<char>]’ at /usr/include/c++/12/bits/stl_vector.h:1779:19,
inlined from ‘constexpr std::vector<_Tp, _Alloc>::iterator std::vector<_Tp,
_Alloc>::insert(const_iterator, _InputIterator, _InputIterator) [with
_InputIterator = const char*; <template-parameter-2-2> = void; _Tp = char;
_Alloc = std::allocator<char>]’ at
/usr/include/c++/12/bits/stl_vector.h:1481:22,
inlined from ‘T::T()’ at test.cpp:17:14:
/usr/include/c++/12/bits/new_allocator.h:137:55: note: at offset 1 into
destination object of size 1 allocated by ‘operator new’
137 | return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n *
sizeof(_Tp)));
